The present invention relates to an image forming apparatus including a temporary paper storage positioned on a transport path, which extends to an image forming section, and conveying a paper sheet into the paper storage with the leading edge of the paper sheet at the head and then switching it back toward the image forming section with the trailing edge at the head. The image forming apparatus may be implemented as a printer, a copier, a facsimile apparatus, or a combination thereof.
It is a common practice with an electrophotographic image forming apparatus to sequentially feed paper sheets from a paper stack to an electrophotographic image forming section along a preselected transport path. The conventional apparatus uses a registration roller pair for matching the paper sheet and the position of an image at a position just short of the image forming section. This, however, brings about a problem when a plurality of paper sheets are continuously fed to the image forming section. Specifically, the paper sheets must be fed at the intervals of 10 mm or so due to irregularity in the position of the leading edge of the paper sheet separated from the other paper sheets, variation in paper conveying speed ascribable to aging and environment, and a period of time necessary for registration to be effected.
In light of the above, Japanese Patent Laid-Open Publication No. 5-289453, for example, teaches an image forming apparatus constructed to accelerate a paper sheet being conveyed along a transport path only for a preselected period of time. The acceleration reduces the interval between successive paper sheets without increasing the speed of an electrophotographic process and thereby enhances productivity as to image formation, However, when the length of the transport path to an accelerating position is great, all the paper sheets existing on the transport path must be accelerated to the same speed. As a result, the apparatus needs large-scale speed variation control and a sophisticated construction while aggravating noise.
Japanese Patent Laid-Open Publication Nos. 8-259045, 8-20106 and 5-97305 each disclose an image forming apparatus of the type forming an image on one side of a paper sheet, then guiding the paper sheet to a switchback path, and then switching back the paper sheet toward an image forming section in order to form an image on the other side of the paper sheet. None of these documents, however, teaches an arrangement in which paper sheets stacked on a cassette, tray or similar stacking section are directly fed to an image forming section by being switched back.
Particularly the apparatus taught in the above Laid-Open Publication No. 8-259045 cannot reduce the interval between successive paper sheets to a noticeable degree because three rollers are sequentially arranged to drive a paper sheet into and out of a paper reversing device such that the conveying speed is identical around the paper reversing device. Further, the position for effecting registration is remote from image forming means and is apt to cause the position of an image to be noticeably shifted due to conveyance errors. The apparatuses taught in Laid-Open Publication Nos. 8-20106 and 5-97305 also use three rollers and cannot reduce the interval between successive paper sheets.
When a paper jam occurs on the transport path of an image forming apparatus, It has been customary to interrupt paper conveyance in the apparatus in order to prevent the paper jam from being aggravated. Assume that a paper cassette loaded with paper sheets allows paper sheets to be replenished with a front-loading configuration, and that a paper sheet extends over both of the cassette and the transport path at the time of a paper jam Then, when the cassette is inadvertently pulled out of the apparatus, the above paper sheet tears and damages the apparatus or brings about another paper jam later.
Technologies relating to the present invention are also disclosed in Japanese Patent Laid-Open Publication Nos. 1-321231, 4-116570, 6-236086, 7-120984, 7-129057, and 7-261608.
It is therefore an object of the present invention to provide an image forming apparatus capable of reducing the interval between successive paper sheets to be fed to an image forming section and thereby enhancing productivity as to image formation.
It is another object of the present invention to provide an image forming apparatus capable of correcting irregularity in the above interval at the time of switchback by controlling a paper conveying speed, thereby further reducing the interval.
It is another object of the present invention to provide an image forming apparatus capable of continuously driving a roller pair, which is a substitute for a conventional registration roller pair, to thereby maintain the interval accurate without resorting to a registering operation.
It is another object of the present invention to provide an image forming apparatus capable of reducing the wear of an image forming section ascribable to a long interval between successive sheets. thereby enhancing productivity.
It is another object of the present invention to provide an image forming apparatus capable of conveying paper sheets in a stable manner.
It is another object of the present invention to provide an image forming apparatus capable of switching a paper conveying speed in a stable manner.
It is another object of the present invention to provide an image forming apparatus capable of obviating the deterioration of paper conveyance ascribable to, e.g., slip occurring when a paper sheet is brought to a stop.
It is still another object of the present invention to provide an image forming apparatus capable of preventing, when a paper sheet jams a transport path, the paper sheet from tearing and damaging the apparatus or bringing about another jam.
It is yet another object of the present invention to provide an image forming apparatus allowing the operator of the apparatus to easily deal with a jam.
It is further object of the present invention to provide an image forming apparatus capable of reducing production cost.
In accordance with the present invention, an image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets, and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette. A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet at a particular speed on each of part of the transport path extending between the paper cassette and the paper storage and part of the transport path extending between the paper storage and the printer engine.
In accordance with the present invention, an image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets, and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette. A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet from the paper storage toward the printer engine at a speed higher than a paper conveying speed for image formation assigned to the printer engine.
In accordance with the present invention, a printer includes an image forming apparatus, an input terminal for receiving image data, and a controller for causing the image forming device to form an image on a paper sheet in accordance with the image data. The image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets, and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette. A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet at a particular speed on each of part of the transport path extending between the paper cassette and the paper storage and part of the transport path extending between the paper storage and the printer engine.
In accordance with the present invention, a copier includes an image scanner for reading a document image, an image forming apparatus, and a controller for controlling the image scanner and image forming apparatus such that the image forming apparatus forms an image on a paper sheet in accordance with image data output from the image scanner and representative of the document image. The image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets. and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette. A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet at a particular speed on each of part of the transport path extending between the paper cassette and the paper storage and part of the transport path extending between the paper storage and the printer engine.
In accordance with the present invention, a facsimile apparatus includes an image scanner for reading a document image, an image forming apparatus, and a transmitter/receiver for interchanging image data with a remote station via a network. A controller controls the image scanner, image forming apparatus and transmitter/receiver such that image data output from the image scanner and representative of the document image are sent to the remote station via the network, or the image forming apparatus forms an image on a paper sheet in accordance with image data received from the remote station via the network and transmitter/receive. The image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets, and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette. A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet at a particular speed on each of part of the transport path extending between the paper cassette and the paper storage and part of the transport path extending between the paper storage and the printer engine.
In accordance with the present invention, a multiplex machine includes an image scanner for reading a document image, an image forming apparatus, a transmitter/receiver for interchanging image data with a remote station via a network, an input terminal for receiving image data, and an output terminal for outputting image data. A controller controls the image scanner, image forming apparatus and transmitter/receiver such that the image forming apparatus forms an image in accordance with the image data received via the input terminal, or image data output from the image scanner and representative of the document image are output to the outside via the output terminal or sent to the remote terminal via the transmitter/receiver and network, or the image forming apparatus forms an image on a paper sheet in accordance with image data received from the remote terminal via the network and transmitter/receiver. The image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets, and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette. A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet at a particular speed on each of part of the transport path extending between the paper cassette and the paper storage and part of the transport path extending between the paper storage and the printer engine.
In accordance with the present invention, a printer includes an image forming apparatus, and an input terminal for receiving image data. A controller causes the image forming apparatus to form an image on a paper sheet in accordance with the image data. The image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets, and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette. A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet from the paper storage toward the printer engine at a speed higher than a paper conveying speed for image formation assigned to the printer engine.
In accordance with the present invention, a copier includes an image scanner for reading a document image and an image forming apparatus. A controller controls the image scanner and image forming apparatus such that the image forming apparatus forms an image on a paper sheet in accordance with image data output from the image scanner and representative of the document image, The image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets, and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette. A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet from the paper storage toward the printer engine at a speed higher than a paper conveying speed for image formation assigned to the printer engine.
In accordance with the present invention, a facsimile apparatus includes an image scanner for reading a document image, an image forming apparatus, and a transmitter/receiver for interchanging image data with a remote station via a network. A controller controls the image scanner, image forming apparatus and transmitter/receiver such that image data output from the image scanner and representative of the document image are sent to the remote station via the network, or the image forming apparatus forms an image on a paper sheet in accordance with image data received from the remote station via the network and transmitter/receiver. The image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets, and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette. A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet from the paper storage toward the printer engine at a speed higher than a paper conveying speed for image formation assigned to said printer engine.
In accordance with the present invention, a multiplex machine includes an image scanner for reading a document image, an image forming apparatus, a transmitter/receiver for interchanging image data with a remote station via a network, an input terminal for receiving image data, and an output terminal for outputting image data. A controller controls the image scanner, image forming apparatus and transmitter/receiver such that the image forming apparatus forms an image in accordance with the image data received via the input terminal, or image data output from the image scanner and representative of the document image are output to the outside via the output terminal or sent to the remote terminal via the transmitter/receiver and network, or the image forming apparatus forms an image on a paper sheet in accordance with image data received from the remote terminal via the network and transmitter/receiver. The image forming apparatus includes a printer engine for forming an image on a paper sheet, a paper cassette loaded with a stack of paper sheets, and a paper feeder for feeding one of the paper sheets toward the printer engine at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper cassette, A paper reversing device positions the paper sheet fed from the paper cassette in the paper storage with its leading edge at the head and then switches back the paper sheet toward the printer engine with its trailing edge at the head. The paper feeder feeds the paper sheet from the paper storage toward the printer engine at a speed higher than a paper conveying speed for image formation assigned to the printer engine.
In accordance with the present invention, an image forming apparatus includes an image forming section for forming an image on a paper sheet, a paper stacking section for stacking paper sheets. thereon, and a paper feeder for feeding one of the paper sheets from the paper stacking section to the image forming section at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper stacking section. A paper reversing device positions the paper sheet fed from the paper stacking section in the paper storage with its leading edge at the head and then switches back the paper sheet toward the image forming section with its trailing edge at the head. A registering device performs a registering operation for adjusting a timing at which the paper feeder should feed the paper sheet and a timing at which the paper reversing device should deliver the paper sheet. As a result, the timing of delivery of the paper sheet toward the image forming section is synchronized to image formation. A paper sensor is positioned in the paper storage for sensing the paper sheet. The paper feeder effects the feed of the paper sheet from the paper stacking section toward the paper storage and the feed of the paper sheet from the paper storage toward the image forming section independently of each other. The registering device performs the registering operation in response to the output of the paper sensor representative of the paper. When. the paper feeder temporarily stops conveying the paper sheet, the registering device conveys part of the paper sheet toward the image forming section to a position where the trailing edge of the paper sheet does not obstruct the entry of a paper sheet following the above paper sheet into the paper storage.
In accordance with the present invention, an image forming apparatus includes an image forming section for forming an image on a paper sheet, and a paper stacking section for stacking paper sheets thereon. A paper feeder feeds one of the paper sheets from the paper stacking section to the image forming section at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper stacking section. A paper reversing device positions the paper sheet fed from the paper stacking section in the paper storage with its leading edge at the head and then switches back the paper sheet toward the image forming section with its trailing edge at the head A registering device performs a registering operation for adjusting a timing at which the paper feeder should feed the paper sheet and a timing at which the paper reversing device should deliver the paper sheet, As a result, the timing of delivery of the paper sheet toward the image forming section is synchronized to image formation. The paper feeder effects the feed of the paper sheet from the paper stacking section toward the paper storage and the feed of the paper sheet from the paper storage toward image forming section independently of each other. When the paper feeder temporarily stops conveying the paper sheet, the registering device conveys part of the paper sheet toward the image forming section to a position where the trailing edge of the paper sheet does not obstruct the entry of a paper sheet following the above paper sheet into the paper storage.
In accordance with the present invention, an image forming apparatus includes an image forming section for forming an image on a paper sheet, a paper stacking section for stacking paper sheets thereon, and a paper feeder for feeding one of the paper sheets from the paper stacking section to the image forming section at a time while separating it from the other paper sheets. A temporary paper storage is positioned on a paper transport path for temporarily storing the paper sheet fed from the paper stacking section. A paper reversing device positions the paper sheet fed from the paper stacking section in the paper storage with its leading edge at the head and then switches back the paper sheet toward the image forming section with its trailing edge at the head. A jam sensor is positioned on the transport path or a transport path following it for sensing a paper jam A stopping device stops the operation of the image forming section and the operation of the paper feeder when the jam sensor senses a paper jam A storing device causes, when the stopping device stops the above operations, the paper feeder to continuously convey the paper sheet being conveyed along the transport path between the paper stacking section and the paper storage to the paper storage. The paper stacking section has a front-loading configuration.